Intramolecular energy transfer in molecules with a large number of conformations.

The equations representing the decay kinetics of fluorescence of a donor luminophore in the presence of an acceptor in the same flexible molecule are discussed. The assumption that distances between luminophores attached to chain ends are not correlated with the relative orientations of luminophores is tested by theoretical calculations for the unperturbed chains Tyr-(Ala)(n)-Tyr with n equal to 4 and 9. It appears that for these chains, in which the conformation is dominated by entropic factors, the above assumption is satisfactory even for chains with a small number of repeating units (n = 4).